Overview

Research in the Imaging Radiobiology Laboratory includes a variety of projects working in synergy towards using image methods to understand radiation and cancer biology and improve treatment of human disease. This work spans a continuum ranging from the engineering of preclinical radiotherapy techniques, development of quantitative image analysis methods, design and evaluation of molecular imaging strategies targeting cancer biology, and finally application of these novel technologies towards elucidating the response of tumors and normal tissues to radiation.

A major theme of the Imaging Radiobiology Laboratory is the development and application of novel molecular imaging techniques toward characterizing tumor initiation, progression, and treatment response. We have implemented a number of molecular imaging methods to accomplish this, including imaging metabolism using magnetic resonance imaging (MR) and positron emission tomography (PET), imaging hypoxia using optical and positron emission tomography (PET), imaging vascularity using MRI and x-ray computed tomography (CT). With this battery of methods, we have characterized the frequency and development of hypoxia in mouse models of lung cancer, evaluated the ability of hypoxia PET to predict response to radiotherapy, and characterized metastasis in models of breast cancer.

In order to study the effects of radiotherapy, it is necessary to have a model of clinical radiotherapy that can be administered to laboratory animals. However, historically radiation has been applied in the laboratory using single field irradiators, producing dose distributions which are far less conformal and precise than those routinely achieved in the clinic. To address this limitation of preclinical research, we have developed a small animal irradiator using a commercial micro-computed tomography (microCT) scanner equipped with a custom-developed variable aperture collimator, motion stage, treatment planning system, and Monte Carlo-based dose calculation engine. We continue to engineer this sytem and explore its use in studying preclinical radiobiology.

A wide variety of imaging methods are now available for preclinical and clinical research, however this explosion of data requires commensurate development of image viewing and analysis methods in order to most efficiently derive meaningful information from these data. In collaboration with colleagues in the Departments of Radiation Oncology and Radiology at Stanford University, we have designed an open-source image analysis tool, RT_Image, to facilitate the exploratory analysis of multimodal imaging data. This tool is now in use by researchers at Stanford and beyond, and has been expanded for applications including small animal radiotherapy treatment planning and dose calculation.